The present invention relates to dynamic viscoelasticity measuring apparatus for detecting the dependence of the viscoelastic property of a material on temperature, time or frequency, and more particularly to apparatus of this type that can improve the accuracy of measured data.
In conventional apparatus of the above-described type, use has been made of sample holders which are held stationary to prevent both ends of the sample from moving in any direction.
However, the above-mentioned prior art technique has exhibited certain problems because of the fact that where the temperature dependence of the modulus of complex elasticity of a sample having a high coefficient of thermal expansion is measured, since both ends of the sample are held stationary, the thermal expansion of the sample is restricted at its ends so that the central portion of the sample deforms in the stress and strain detecting direction, in the direction normal to the detecting direction, and in the direction normal to the longitudinal direction of the sample. The following specific problems occur:
(1) The shape of a sample required for a basic formula to calculate the modulus of complex elasticity of the sample is a parallelepipedon or a column so that if the sample bends due to its thermal expansion, a measurement error will result; and
(2) As the sample deforms in the stress and strain detecting direction, the central position of the strain detection shifts with the thermal expansion of the sample and this requires the provision of a complicated mechanism for detecting the central strain detecting position.